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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

What has global warming done since 1998?

What the science says...

Every part of the Earth's climate system has continued warming since 1998, with 2015 shattering temperature records.

Climate Myth...

It hasn't warmed since 1998
For the years 1998-2005, temperature did not increase. This period coincides with society's continued pumping of more CO2 into the atmosphere. (Bob Carter)

Even if we ignore long term trends and just look at the record-breakers, 2015, 2014, 2010, and 2005 were hotter than 1998.

The myth of no warming since 1998 was based on the satellite record estimates of the temperature of the atmosphere. However, as discussed in the video below by Peter Sinclair, even that argument is no longer accurate. The satellites show warming since 1998 too.

There's also a tendency for some people just to concentrate on atmospheric or surface air temperatures when there are other, more useful, indicators that can give us a better idea how rapidly the world is warming. More than 90% of global warming heat goes into warming the oceans, while less than 3% goes into increasing the atmospheric and surface air temperature. Records show that the Earth has been warming at a steady rate before and since 1998 and there is no sign of it slowing any time soon (Figure 1).

Even if we focus exclusively on global surface temperatures, Cowtan & Way (2013) shows that when we account for temperatures across the entire globe (including the Arctic, which is the part of the planet warming fastest), the global surface warming trend for 1997–2015 is approximately 0.14°C per decade.

Ultimately, every part of the Earth's climate system is warming, and has continued warming since 1998.

Further viewing

Comments

Speaking as someone who did qualify as a Mechanical Engineer, I suppose I should step in to defend my profession. Mechanical Engineers, perhaps more than any other branch of engineering are actually uniquely qualified to evaluate climate science. So long as they are prepared to go back to their roots; to the core subjects they studied.

Mech Engies don't just deal with gear trains and machinery. At it's core is a lot of study of thermodynamics, fluid mechanics, physics, maths etc. Other branches of engineering have a different balance. Electrical engineers don't do much fluid mechanics, Civil engineers don't do as much thermodynamics, etc.

The problem for Mechanical engineers is that we tend to get channelled into dealing with machinery in our working lives and put the underlying core science we learn't on the back burner. If a Mech eng' can go back to their original training they have all the tools needed to assimilate climate science. As examples:

Heat Transfer - the Earth's Radiative Balance for example

Viscosity - how the wind imparts a shear force on the oceans and in turn shear forces within the oceans generate Ekman Transport.

I would imagine that the apparent increased incidence rate of denialism among engineers and geologists has less to do with the curriculum or knowledge base of those disciplines and more to do with the industry they often find themselves working within.

Tristan @302, it is not just the industry (or not just the industry). Engineers (and doctors) are disproportionatly represented among creationists as well. I think what happens is that the engineers are aware that they have a good technical education in areas that are closely related to science. However, they are taught those skills as a recieved body of knowledge, so that they do not train themselves to not decieve themselves when it comes to science. That leaves some engineers (and by no means all, or even most) prone to assume they can speak authoritatively on a subject that they do not understand.

Nor should it be believed that this is a disease that only afflicts engineers, although the etiology is no doubt different for physicists:

Finally, I agree with Glenn Tamblyn - engineers not afflicted with this peculiar arrogance do have the skills to understand climate science quickly and well. They just have to be prepared to learn first.

Let me just say I am not skeptical of the fact the globe is warming so don’t think my comment is guided by that bias, but I do see a lack of predictability that I know is being worked on.

I too am an engineer. I’m not going to discuss in depth the notion that mechanical engineers have an unusual variation in skill. I assume the belief held by bozzza is that all scientists are equally brilliant and some of them haven’t barely gotten by in school? Futile point to say the least. There are poor scientists and poor engineers. Not realizing that is disappointing. I am not surprised how several people comment on the profession like it is subordinate. Many engineers view scientists the same way, but it is seen as a study that is ignorant of application, blind beyond their own work/views, completely void of practical understanding, and contributes nothing directly to the world. I’m kidding mostly – so relax.

But my point is that after decades of engineering research and enormous amounts of time working for/in/with teams of many different disciplines and backgrounds both scientific and engineering, the thing I have found to be a problem across the board is the lack of understanding most people have of their own inabilities. I have seen people work on something for 10 years and think they understand every facet of the topic because they explained why something has happened in the past, but couldn’t predict a thing. But the truth is their models were terrible and without a practical view they would never understood that and improve.

I have never seen an accurate prediction of global temperatures over any appreciable period of time. We should be very grateful for skepticism. Without it we would be worshiping the sun and sacrificing each other. Skepticism drives improvement. Blind faith in modeling is a very serious problem and outside academia (or at least in industry where the risk of error is critical as it should be for global warming) this is well understood.

The key question isn't about a lack of predictbility. It is about what is reasonable to be able expect of prediction. If models are achieving the degree of predictability that one would expect of them given the nature of the problem being studied, then they are doing pretty well.

As an engineer, do you regard the acceptance of the basic Conservation Laws - Energy, Mass, Momentum etc - as 'blind faith'? Because that is what climate is; the application of the basic laws of physics. At its very simplest, Climate is an application of the 1st Law of Thermodynamics.

If we maintain the energy flow into a system while restricting energy flow out of that system, is expecting that the total energy within the system will increase, and thus tmperatures increase 'blind faith'? Is the 1st Law 'blind faith'?

JohnD wrote, "I have never seen an accurate prediction of global temperatures over any appreciable period of time."

This can only be true if you haven't looked very hard or are definining 'accurate' and/or 'appreciable' in ways that I would consider unreasonable. I mean, look at the list of top climate myths at the upper left part of this page. Number six is 'Models are unreliable'.

Climate models can not predict volcanic eruptions or fluctuations in various cycles (e.g. ~11 year solar cycle, ~30 year PDO, et cetera)... which is why they do multiple runs assuming different variations for these factors. Observed warming has consistently been within the range shown by those scenarios, and when you plug in a scenario matching the actual unpredicted variations you get results matching the actual observations. If that isn't 'accurate' then you're using the word in a way which reverses its most common meaning.

John D, skepticism is a good thing indeed, when it is sincere. Refusing to acknowledge an entire body of evidence because one dislikes what it implies is not skepticism. Believing ideas that are not supported by evidence because they are more appealing or conform to one's preferred ideology is not skepticism. Stating that, in essence, one's ignorance is just as good as a bunch of other poeple's expertise is not skepticism. Choosing to trust an isolated fruitcake or a charlatan vs a large number of experts with converging results is not skepticism. The last time that I know of that a skeptic went about it with sincerity, the result was the BEST study. That's sincere.

You make claims of "blind faith" and inaccurate predictions that beg for further development. The thread mentioned higher would be the place to go for that.

It's childish and unnecessarily insulting to suggest I don't understand concepts of conservation laws. Perhaps poor reading comprehension by some lead to that conclusion. I’m not sure. But I never suggested the concept was wrong or I didn’t make sense to my weak and feeble mind. And the thought that I don’t understand that a complex system is difficult to predict or understand instrumentation errors and sensitivities is ridiculous because that is my point…

I do indeed believe that it has to be a fact that CO2 has many negative effects (and really I thought I made that obvious and even stated that to begin with). Like I said however, what is disturbing to me is the religious-type fervor on the subject in particular the condescension (such as insulting people’s intelligence over expressing a caution when trusting a model that cannot be validated except over time) and lack of good predictability (using early 2000s as a reference for myself). I only posted because the pretentious attitudes and condescension are disgusting. I did not suggest it is not a problem. But it is important to remember that there has to be a large band of confidence by any model with so many factors.

Perhaps a major issue is only the poor predictions are making it to the media, but all I have seen in the past is the extreme scenarios that has not panned out. I’m not going to devote large amounts of time to researching this because it’s better for me to devote my time to my own industry, but I am skeptical of the level of confidence many have in the problem’s *rate* not its existence and the fervor around predictions. I’m not even saying that it’s overstated… I’m just saying there cannot be an enormous level of confidence in the rate in which the effects of the added heat occur. If someone posts again that I don’t understand the concept of a closed system or the 1st law, then I will be disappointed. The questions I raise are about the confidence in rates not the mechanism.

Response:

[JH] You make numerous assertions in the above, some personal and some about the science. The tone of you personal assertions is argumentative and this argumentative tone should not be repeated in you future posts. Your assertions about the science are undocumented. If they are merely your personal opinion, they have little value in this venue.

There are large confidence intervals for many of the projected future scenarios. Those confidence intervals aren't hidden. Fortunately, climate science isn't confined within any single paper or projection. The current state of climate science represents a consilience of evidence from thousands of papers. Most climate scientists aren't saying 'exactly x will happen by year y', they are saying 'these are the range of things that are likely to happen, given current trends and models based on physical constraints, and it is smart money to acknowledge these likelihoods'.

Two points. First I don't think the post you're responding to was suggesting that you did not understand the first law of thermodynamics. In fact, it was presuming that you did understand it. The point was that what confidence modelers have comes from the application of relatively simple laws of physics, albeit impliemented in a complex context. What looks like religiosity to you many stem from the confidence in those laws.

Second, until we understand what you are specifically talking about with respect to poor predictions, it's hard to discuss you concerns. For the most part models have done pretty well, especially when the inputs actually reflect reality. They certainly do well enough to discern a human influence on climate vs a natural one. Projections forward are very much dependent on basically random events like volcanoes and El nino and by the actions of humans, which may be influenced by the models.

If you gave us some specifics people could respond more constructively.

JohnD wrote: "Perhaps a major issue is only the poor predictions are making it to the media..."

You have yet to identify, let alone substantiate, even one of these supposed 'poor predictions'. Until you do so it is not 'pretentious and condescending' to dismiss your position... because you have not presented a position.

Try to look at it from the other side. People who do not consider themselves to be acting on "blind faith" and "religious-type fervor", but rather accepting the strong scientific consensus based on the overwhelming evidence. Then you come in proclaiming that they are all wrong, while refusing to cite any evidence for your position and ignoring evidence to the contrary provided to you. Some might call such behaviour 'pretentious and condescending'.

I am a recent convert to AGW skepticism but am still trying to keep an open mind.

Following are two quotes by prominent global warmists accepting that atmospheric warming has had no statistically significant increase since the El Nino of 1998

Met Office Blog – Dave Britton (10:48:21) – 14 October 2012“We agree with Mr Rose that there has been only a very small amount of warming in the 21st Century. As stated in our response, this is 0.05 degrees Celsius since 1997 equivalent to 0.03 degrees Celsius per decade.”Source: metofficenews.wordpress.com/2012/10/14/met-office-in-the-media-14-october-2012

Dr. Hans von Storch – IPCC lead author - Spiegel – 20 June 2013“…the increase over the last 15 years was just 0.06 degrees Celsius (0.11 degrees Fahrenheit) — a value very close to zero….If things continue as they have been, in five years, at the latest, we will need to acknowledge that something is fundamentally wrong with our climate models….”

“So far, no one has been able to provide a compelling answer to why climate change seems to be taking a break.”

But your article above is saying that we should be looking at the heat going into sea to determine "global warming".

However the IPCC's sole target is to keep atmospheric CO2 concentrations to within 2Deg C of preindustrial levels and if we add the 0.8DegC that the planet warmed prior to this century(0.8 degC), to the projected increase based on Hans Von Storch's figure above of 0.06 per 15 years then that gives us 0.8 + 0.06* 100 / 15 = 0.8 + 0.4 = 1.2 DegC which is well within the 2.0 DegC limit.

Seems to me that AGW is unfalsifiable. When temperatures were rising in the 1990's that was proof of AGW, but now that temperatures have plateaud so far this century, the "proof" of AGW moves elsewhere.

One last question...If global temperature increase stays at the present near zero rate until 2100, will the theory of AGW need revision?

Peter, your account will be deleted if you persist with the "testing" garbage.

You're going to get plenty of response, and hopefully you'll engage honestly in dialogue. Here's the short version of what you're going to get:

1. Regardless of the language people are using, 93%+ of the thermal capacity of the climate system is wrapped up in the oceans.

2. Surface temp is noisy. As you can see from the "elevator," there have been many 6-8 year periods of insignificant or even negative trend over the last forty years.

3. 1998 is a cherry pick with regards to statistial significance. If you start a trend on a massive outlier, statistical significance is going to be hard to establish for a while.

4. Even so, look at the surface trend from 1970-2008. It's 0.178C per decade, right about the expected trend. How can that be! How can it be thus if there has been no significant warming for 17 years! It can be thus because the actual "pause" is not 17 years but more like seven years.

5. Start with the physics, like a real skeptic. Do you understand the greenhouse effect?

Bit puzzled by your incredibly hostile and accusatory tone. This is my first time at your site and he two "testing" comments were because I was on page one and didn't see my comment appear as it was on page 7. Bit thick of me but why do you instantly attack me.

You say I have got the pause wrong but I quoted the UK met office and Hans Von Storch of the IPCC saying that the pause is real. Why attack me for their quotes?

Instead of personal attacks on me, could you please address specifically what I said in my first comment. Thanks.

The "testing" comment could have been read as impatience. I was signaled to read it that way by your substantial comment. In that comment, you focus on the language being used and do not show how the language is at odds with the science. You simply pit the language of those linked against the language of SkS. If you were truly skeptical, you'd be checking the language used against the actual science.

I did not claim there was no "pause." Indeed, I pointed out that there were others. However, my claim was that the pause was in global mean surface temperature and not in the overall (well, sub-stratospherical) climate system.

Hans Von Storch is simply wrong in applying "pause" to "climate change." Climate change and global warming aren't even the same thing (rather obviously, as there is more to climate than temp). Even if the enhanced greenhouse effect was done being enhanced, climate change would still be taking place--and would until the entire system came to equilibrium with the new level of forcing. Von Storch was being careless.

As for the Met Office quote, I can only assume that you snagged the quote from somewhere other than the Met blog post, as the post explains everything in detail.

Q.1 “First, please confirm that they do indeed reveal no warming trend since 1997.”

"The linear trend from August 1997 (in the middle of an exceptionally strong El Nino) to August 2012 (coming at the tail end of a double-dip La Nina) is about 0.03°C/decade, amounting to a temperature increase of 0.05°C over that period, but equally we could calculate the linear trend from 1999, during the subsequent La Nina, and show a more substantial warming.

"As we’ve stressed before, choosing a starting or end point on short-term scales can be very misleading. Climate change can only be detected from multi-decadal timescales due to the inherent variability in the climate system. If you use a longer period from HadCRUT4 the trend looks very different. For example, 1979 to 2011 shows 0.16°C/decade (or 0.15°C/decade in the NCDC dataset, 0.16°C/decade in GISS). Looking at successive decades over this period, each decade was warmer than the previous – so the 1990s were warmer than the 1980s, and the 2000s were warmer than both. Eight of the top ten warmest years have occurred in the last decade.

"Over the last 140 years global surface temperatures have risen by about 0.8ºC. However, within this record there have been several periods lasting a decade or more during which temperatures have risen very slowly or cooled. The current period of reduced warming is not unprecedented and 15 year long periods are not unusual."

Peter99 @316, you are not a skeptic of the theory until you apply as much skepticism to criticisms of the theory as you do to the theory itself. Had you done so, and using the HadCRUT4 data, you would have noted that the temperature trend from 1975 to 1997 was 0.16 C per decade, while the temperature trend from 1975 to current is 0.17 C per decade. That is, the seventeen years of "temperatures [being] plateaued" has increased the trend by 6.25%.

This must be the first time in history that a decrease in the slope (the temperature plateauing) has actually increased the slope.

The reason for this unusual result is not hard to find. It is that you have been conned. Specifically, if you take a series with no overall trend and random fluctuations about the mean value, and look only at those segments which start at a local peak value above the mean, on average those segments will have a negative trend. If you only look at those segments that start well above the mean value and finish well below the mean value you might even find segments that show a statistically significant negative slope. That will not prove that the line does not exhibit no trend. It will only prove that you have cherry picked your start and end points.

That is exactly what the purported "skeptics" of AGW have done. They take an interval starting with a random fluctuation above the trend value due to the strongest or second strongest El Nino event on record (depending on which index you use). You then take the interval to a period containing one of the strongest La Nina events on record (2011/12), and which is consequently below trend values. They then treat that segment as important, even though the trend in that period is not statistically different from IPCC projections, let alone the ongoing long term trend.

On top of that they add a little verbal legerdemaine. They start by saying that in that period the trend is not statistically different from zero; and end by talking about a period with no trend ("trend has plateaued", "global warming has stopped"). The trend, however, is not statistically distinguishable from IPCC projections, so that it is no more true to say the trend has plateaued than to say it matches IPCC projections. This they are carefull not to mention.

So, please prove that you are in fact a skeptic about AGW, and apply your skepticism both ways. If you do so, you will stop buying the rubbish you just tried to propogate here and start wondering why the arguments of so-called AGW skeptics are so often indistinguishable from bald-faced lies.

OK, points above taken. Let's eliminate the 1998 El Nino and only do a calculation for this century. I used your calculator and put in start date of 2000 and end date of 2105 for both RSS and UAH.RSS gave -0.0048/year and UAH gave +0.0066/year.Let's use the high figure of 0.0066/year which of course means 0.66 DegC rise for 2000 to 2100. Let's add that to the 0.8DegC rise up to 1999 and that gives 1.46 DegC rise from 1900 till 2100.Of course the above assumes that the current rate so far this century will continue. But getting back to the point I made in my original comment, this will be significantly less than the IPCC target of 2.0DegC. So should this target be retained or changed to reflect heat entering the ocean?

Sorry again as I've been rushing this as I have to go out just now. The start date I chose was 2001 becasue to pick 2000 would have been cherry picking for AGW as there was a steep decline after the El Nino. Selecting 2001 as a start date seems to me to be a fair compromise if you look at the graphical trend.

Petter99 @324, the UAH trend from 2001 to current is 0.070 ±0.217 °C/decade. That compares to an IPCC projected trend over the interval of 0.2 °C/decade. That is, it is well within error of the IPCC projection. That the error margin on measurement is larger than the projected temperature rise, however, tells you that it is too short a period to test the theory.

The RSS data should be ignored. It uses the same basic data as UAH but the processing results in values distinctly different not only to UAH, but also to all other temperature records. Until it is found out why that is, and a correction made, it must be regarded as inaccurate for short term trends.

Beyond that, by shifting forward the start point to 2001, you eliminate the large El Nino at the start of the series, but increase the impact of the large La Nina at the end of the series. Ergo, based on what we know about climate states about the world, we know that that trend is low due to short term variability rather than due to a low value in the underlying trend. Indeed, without AGW, we would have expected the trend to be strongly negative. (That still makes it an improvement over the previous post. The claim based on 1998 can be refuted by statistics alone. With regard to a 2001 start, you need to know something more about the climate system than is contained in the temperature data itself.)

If you want to know what the trend is like without the impact of ENSO states, the simplest method is to compare the trends for El Nino year, La Nina Years, and neutral years:

As you can see, they are very similar, quite close to the IPCC projection, and have not changed in recent years. What has changed is that we have got more than usual La Nina years of late following on froma period of slightly more than usual El Nino years.

As to why we shoud not simply project the recent temperature trend, the forcing from GHG is not expected to remain constant, or increase linearly over the 21st century. Ergo it is silly to expect temperature trends to continue as though they are going to increase linearly. Particularly if you take a short term trend known to be reduced by a late occuring La Nina to project it. If you are going to project statistically from the temperature record, you should determine the relationship between forcings and that temperature record and then project according to the assumption that the relationship between forcings and temperature record will remain fairly constant. Dr Cowtan has a model that allows you to do this. You can even scale the forcings to see if you can get a better fit to temperatures than that embodied in the assumption that temperatures respond equally to all forcings. Good luck finding a fit that doesn't either obviously fail relative to the intuitive assumption of equal effect from different forcings over past temperatures, or else more or less reproduce IPCC projections.

Further, Peter, you claim to be an "AGW skeptic," but your argument is in regards to climate modeling. The theoretical basis of AGW does not emerge from climate modeling. The theory of AGW is simply that humans have enhanced the greenhouseeffect, causing greater-than-natural warming. Climate modeling--and here I'll refer specifically to comprehensive general circulation modeling--projects climate change on the multidecadal scale and at fairly low resolution. The resolution is getting better (in some ways) in both time and space, but accuracy is not at the subdecadal scale yet.

All models of real world phenomena are inaccurate. Are they also then failures? If you take a step back and look at where the observed trends could have reasonably gone based simply on past history (a layperson's heuristic), you'd be forced to come to the conclusion that climate modeling has done remarkably well with projecting temp, sea level rise, OHC, etc. (not Arctic sea ice area/extent).

"I find these similarities remarkable, because none of these patterns are coded into the climate model – they all emerge as a consequence of getting the basic thermodynamic properties of the atmosphere right. Remember also that a climate model is not intended to forecast the particular weather of any given year (that would be impossible, due to chaos theory). However, the model simulates a “typical” year on planet earth. So the specifics of where and when each storm forms do not correspond to anything that actually happened in any given year. But when the model gets the overall patterns about right, that’s a pretty impressive achievement."

Anyway, any further discussion of modeling should be taken to one of the modeling threads. You can see all new comments across all threads by clicking on the "comments" link below the middle of the SkS header.

You've already had Tom and DSL give you fairly lengthly replies. I will not add to much to the fray, as one of this site's policies is to try to prevent "dog-piling" - a case where an individual gets a large number of responses from many people, which can be overwhelming.

...but, in comment #326, you said "Selecting 2001 as a start date seems to me to be a fair compromise". Taking a skeptical approach, what does the following suggest to you:

picking 1998, 1999, 2000, or 2001 as the starting year makes a large difference in the trend that is calculated.

Should this not be a warning signal that you should not put a lot of trust into any of these numbers, when trying to examine a long-term warming signal?

Global temperatures seem to have plateaud. It is not only skeptics saying this, but many prominent warmists such as…

Dr. Kevin Trenberth – CRU emails – 12 Oct. 2009“Well, I have my own article on where the heck is global warming…..The fact is that we can’t account for the lack of warming at the moment and it is a travesty that we can’t.”

Dr. Phil Jones – BBC – 13th February 2010[Q] “Do you agree that from 1995 to the present there has been no statistically-significant global warming”[A] “Yes, but only just

Dr. James Hansen – NASA GISS – 15 January 2013“The 5-year mean global temperature has been flat for a decade, which we interpret as a combination of natural variability and a slowdown in the growth rate of the net climate forcing.”

Notice they all acknowledge the pause and Hansen gives his “pause” interpretation. But apart from Hansen’s theory, there have been over 60 other different theories/reasons trying to explain where the “missing heat” has gone. But which one is correct? If the science is settled why are there so many and varied theories?

Hans von Storch is no AGW lightweight and to dismiss his quote above as “careless” is a bit presumptuous. Let me repeat the quote…

Dr. Hans von Storch – IPCC lead author - Spiegel – 20 June 2013“…the increase over the last 15 years was just 0.06 degrees Celsius (0.11 degrees Fahrenheit) — a value very close to zero….If things continue as they have been, in five years, at the latest, we will need to acknowledge that something is fundamentally wrong with our climate models….”“So far, no one has been able to provide a compelling answer to why climate change seems to be taking a break

Did a very senior IPCC author get it wrong? If the pause continues for another 5 years will it be acknowledged that climate models have a fundamental problem as he claims? He obviously doesn’t think any of the 60 or so “missing heat” theories are “compelling”.

So my question is, if the pause continues, how many years must pass before it’s conceded that “something is fundamentally wrong with our climate models”? In other words, if the pause continues for n years then can that then be classed as a falsifiable criterion for AGW?

Response:

[JH] You are now skating on the thin ice of excessive repitition which is prohibited by the SkS Comments Policy.

Please note that posting comments here at SkS is a privilege, not a right. This privilege can be rescinded if the posting individual treats adherence to the Comments Policy as optional, rather than the mandatory condition of participating in this online forum.

Please take the time to review the policy and ensure future comments are in full compliance with it. Thanks for your understanding and compliance in this matter.

Peter, there is no 'pause' in any meaningful sense. CO2 hasn't magically stopped re-radiating thermal radiation.

Tom's graph demonstrates the illusory nature of the pause. Things can look like 'pauses' when you have an oscillation (weather) overlaid on a gradient (climate). Just because you can draw flat or negative lines starting from certain peaks to certain troughs doesn't mean that the underlying gradient has changed.

You will note that if you asked that exact question of Phil Jones today, he would be able to answer "since 1995 there has been statistically significant warming in the Surface Temperature Records". At some point within the next 5 years, you'll be able to say the same thing about 1998, and then the so-called skeptics will have to completely reject the surface temperature records, as they will no longer be convenient. Is that the team you want to be on, Peter?

Peter: "So my question is, if the pause continues, how many years must pass before it’s conceded that “something is fundamentally wrong with our climate models”? In other words, if the pause continues for n years then can that then be classed as a falsifiable criterion for AGW?"Peter, let's not be ham-fisted about this, eh? The greenhouse effect is extremely well-established. It's been directly measured from the surface. And I don't think you want to argue that humans aren't responsible for most, if not all, of the increase in atmospheric CO2 over the last century. The general theory of AGW is not going to be falsified by the trend in surface temperature. CO2 does what it does. We have done and are doing what we've done and are doing.

What the trend in surface temp tells us is how well we've modeled energy circulation for Earth's climate system. It also helps us understand climate sensitivity past and present. If the surface trend goes flat or negative for thirty years, then it will indicate that we are missing a major factor in the climate process. If ocean heat content also goes flat for thirty years, then we've likely completely misunderstood the process.

Note that OHC (in the link I posted earlier) in no way shows a "pause." The oceans are still rapidly accumulating energy, and the oceans are 93%+ of the thermal capacity of the climate system.

As Tom has pointed out, and as several of your quotes--in fuller form--point out, drawing conclusions from a surface trend is tricky business. When does the thirty-year trend start? 1998? Not statistically sound, as Tom has pointed out. Trend is negative from x to y (a period of between 6 and 10 years)? So what? Happened before, as I pointed out. Trend is not statistically significant? Ok, but what exactly does that mean? Does it mean that the trend is not statistically distinguishable from zero, or does it mean that it's not statistically different from well above the expected trend? Both. It doesn't mean there's no trend (i.e., it doesn't mean what you think it means).

Your interest seems to be "falsifying AGW" rather than understanding the science. You shouldn't attack something you don't understand. Understanding the theory of anthropogenic global warming by working backward from the surface trend is a bad idea. You should start with the basics. When you start with the basics, you'll know what is "settled science" and what is still being actively researched.

In this latest comment, you're basically repeating the same argument. Tom has answered the question you just asked, and in detail. If you repeat it again, without recognizing what has been said in response, your posts will be in violation of the SkS posting policy.

And yes, Tom, I know we can argue about what exactly is contained within the "theory of AGW," but I don't think it applies in this case. I think it's best to establish that the greenhouse effect is pretty solid, and that we are enhancing that effect. If Peter will oblige us by accepting those two propositions, we can move much more quickly into areas with greater uncertainty (e.g. modeling). I would like Peter to do what many "skeptics" find so hard to do: recognize and accept the basic science.

"Planned adaptation to climate change requires information about what is happening and why. While a long-term trend is for global warming, short-term periods of cooling can occur and have physical causes associated with natural variability. However, such natural variability means that energy is rearranged orchanged within the climate system, and should be traceable. An assessment is given of our ability to track changes in reservoirs and flows of energy within the climate system. Arguments are given that developing the ability to do this is important, as it affects interpretations of global and especially regional climate change, and prospects for the future."

In other words, Trenberth was calling our ability to track energy in the climate system a "travesty." We need better measures of deep ocean heat content, for example. If you just read the quote from some "skeptic" site, then shame on you for not digging for context.

2. Phil Jones. He was answering honestly. The trend was not statistically different from zero. It was also not statistically different from the expected trend. Guess how it was portrayed by those who wish to turn doubt into profit? Again, if you took it hook, line, and sinker, without checking out what "statistically significant" means, and without taking Jones at his word in response to the flabber that followed, then shame on you.

3. Hansen. Be careful: "slowdown in the growth rate of net climate forcing" is not equal to "global warming has stopped/slowed." It may mean that forcing from greenhouse enhancement remains steady but aerosol forcing has increased. What does it mean to you, after having read Hansen's full statement? Or have you read it . . .

It doesn't really matter whether or not you think my explanation is 'one of sixty or so'. There are numerous oscillatory systems at play in weather, from the very short term (day/night) through seasonal differences and the decadal scale PDO (which is responsible for a lot of the year to year climate variation).

You need to learn the meaning of statistical significance before you start making claims about it, lest you look silly.

The trend (GISTEMP) for 1995-2010 is

+0.138 +/- 0.147 c/dec. Because the number after the +/- (the 2 sigma error) is larger than the number before it (the trend), you cannot statistically exclude zero.

The trend (GISTEMP) for 1995-2015 is

+0.113 +/- 0.092 c/dec. Because the error is smaller than the trend, you can statistically exclude zero.

Hence. To 2010 there is not 'statistically significant warming' and to 2015 there is.

"Scientists at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California, analyzed satellite and direct ocean temperature data from 2005 to 2013 and found the ocean abyss below 1.24 miles (1,995 meters) has not warmed measurably. Study coauthor Josh Willis of JPL said these findings do not throw suspicion on climate change itself.

"The sea level is still rising," Willis noted. "We're just trying to understand the nitty-gritty details."

"Coauthor Felix Landerer of JPL noted that during the same period warming in the top half of the ocean continued unabated, an unequivocal sign that our planet is heating up. Some recent studies reporting deep-ocean warming were, in fact, referring to the warming in the upper half of the ocean but below the topmost layer, which ends about 0.4 mile (700 meters) down. "

Note that these quotes are attributed to the study authors. Your earlier quotes in contrast are commentary by the author of the NASA news release with no attribution to the actual study authors.

You said there was a NASA report. Rather it looks like there was a study conducted by scientists from NASA and published in the scientific literature in the normal way. Then the NASA media unit published a news report highlighting the study. Not a NASA report. And maybe the NASA journalist got some stuff wrong!

Like in particular, that the common suggestion of warming occurring 'deeper' has always referred to the lower levels of the upper half of the ocean. Specifically below 700 meters but above 2000 meters. There has been no significant suggestion that meaningful warming is occuring in the lower half of the ocean, below 2000 meters. And this study provides support for that view.

"Seems to me that AGW is unfalsifiable. When temperatures were rising in the 1990's that was proof of AGW, but now that temperatures have plateaud so far this century, the "proof" of AGW moves elsewhere."

You seem to be misunderstanding falsifiability. Key to it is the making of reasonable predictions, understanding the accuracy with which the prediction can be made. Then evaluating all the available data to compare with the prediction. Several key things need to be considered:

Is the theory making a simple black and white prediction; is that a valid statement of the theory? Or is it predicting results within a range of values?

What range of results constitute validation of a theory? What range of results an invalidation? Is there a black-and-white distinction between the two or shades of grey?

Is the nature of the theory such that a failure to completely meet every prediction should be taken as an indication of the total failure of the theory. Or are there degrees of failure and degrees of prediction.

Falsifiability is a great idea but when treated as too black-and-white a criterion it becomes practically useless in many real world scientific contextx. Very few situations lend themselves to black-and-white arguments

So to your question: "One last question...If global temperature increase stays at the present near zero rate until 2100, will the theory of AGW need revision?"

Yes.

But which part of the theory? The part of the theory dealing with Radiative Heat Transfer, Planetary Energy Balance, the Greenhouse Effect etc.? Or the part of the theory dealing with Oceanography, heat distribution in the ocean, ocean overturning time etc?

What if air temperatures don't rise by 2100 but ocean heat content, sea level etc. do rise? Which part of the theory needs to be revised?

You seem to be trying to reduce a complex question down to the idea of the simple black-and-white falsifiability of a single, indivisible theory. When the reality is of a set of multiple intersecting theories, each contributing to the overall conclusion, and complex layered observations that they are being tested against.

Popperian Falsifiability is an important ideal in science; as an ideal! Highly applicable in simple contexts, less useful in more complex situations.

As with most areas in life, basic principles derived from a black-and-white world view only become useful when translated into a shades-of-grey world view. Till then they remain mere idealisations.

If its true that air heats up easier than water and heated air expands and rises , why would the Oceans store the heat and not the air ? What is the flaw in my logic ?, Does not heated water also expand and evaporate ?, Is the oceans heating up begin at the surface where the sun and the air have 1st contact ? If true then why is the heated water sinking down ?, is heated water heavier than cooler water ?, in my bath tub , the cooler water is at the bottom when it sits for a while before i get in, if i don't disturb the water and cause the warm and cold water to mix , i can let the cold water drain out , i'm not trying to prove anything, this is what i observe and what i was taught, i would like to be corrected any where i'm wrong, i have no desired comclusion , i desire only the facts and truth

Response:

[Rob P] - The thermohaline circulation (partially explained by Tom Curtis) also has a wind-driven component to it. In areas of surface water convergence (the subtropical ocean gyres) the water cannot go anywhere else but down into the ocean interior. This is known as Ekman pumping and is a consequence of the fact that we live on a rapidly rotating sphere - something known as the Coriolis Effect. There is no magic taking place in the subtropical ocean gyres, the warmest water is still at the surface.

1) The upper ocean is heated by short wave radiation (visible light) from the sun. It cools by evaporation and by radiation of IR energy. Obviously the rate of cooling depends primarilly on its ability to transfer net energy from its skin layer to the atmosphere (which absorbs most of that IR energy). If you warm the atmosphere, you restrict the rate at which it can cool. Ergo it must warm to gain a new balance between incoming solar energy and outgoing (IR and evaporative) energy.

2) Cold water sinks because it is more dense. But salty water is more dense as well. When ice forms in the arctic (or antarctic) winter, the water becomes more dense due to the excess salt left behind by the freezing process, and sinks. (The arctic and antarctic water is already unusually salty because of evaporation as it travels from the equator). Further, winds over the ocean can generate substantial force. They act in some ways to drive surface waters to depth. I am, however, very unfamiliar with that process, so you are better of asking Rob Painting for details.

@ 338, hot water doesn't rise: because it is energised and is relatively free to move due to its liquid state it moves in random directions allowing cold water to sink through it which conversely is moving in basically only one direction- that being down.

Is this density? I suppose it is!

The concept of hot water rising is not correct, apparently, though there is a concept called "Flotation": but the reality is a warmer body of water is spreading out due to it's more energetic state and if a cooler body of water happens to be sitting on top it will fall through it due to gravity having a stronger influence over the colder waters behaviour.

Of course the warm water is not sinking: heat energy doesn't belong anywhere- it moves from one object to another unlike the quantity we call mass which stays with the object being considered. (I forget the name for this idea..) When the heat energy moves out of the body of water you have under consideration (this is why dashed lines are drawn around things: it's called a system boundary and represents the system/body of water you are talking about) then this water will be sinking due to gravity.

Tom Curtis@327. I'm in an ongoing "exchange" with a skeptic who believes man's influence is there, but very minimal. He recently posted this:

"The 18 plus years of no warming, and the more than a decade of cooling, are factual data from the current version global satellite lower troposphere temperature anomaly datasets from both RSS and UAH(v6). Atmospheric temperature readings by satellite are NOT "surface station" temperature readings.

Go to woodfortrees dot org and plot the past 18 years, 5 months of RSS MSU/AMSU TLT global temperature and you will see not only has there been no warming for that period of time, but the past 14 years have been progressively cooler, and all are cooler than 1998."

I realize the 1998 cherry-pick, but could you please elaborate on these comments of your's?:

"the UAH trend from 2001 to current is 0.070 ±0.217 °C/decade. That compares to an IPCC projected trend over the interval of 0.2 °C/decade. That is, it is well within error of the IPCC projection. That the error margin on measurement is larger than the projected temperature rise, however, tells you that it is too short a period to test the theory."

What is the trend looking back further...how far previous to 1998 can you go with this UAH trend and what would it be?

"The RSS data should be ignored. It uses the same basic data as UAH but the processing results in values distinctly different not only to UAH, but also to all other temperature records. Until it is found out why that is, and a correction made, it must be regarded as inaccurate for short term trends."

Can you provide more detail on what is different about the data processing which results in distinctively different values for RSS vs. UAH?

1) The entire earth system is accruing heat. To try to disprove that by looking at the lower troposphere alone is a bit silly. As most of the heat (95%) goes into the ocean+ice caps looking at a graph of sea level is going to be more useful (it tells you about the rate of thermal expansion and meltwater).

2) if you look in the 'resources' section of the website, and use the trend calculator to plot the RSS trend from 1997, you get a range of +0.17c to -0.17c / dec. Now, if your friend wants to call that cooling, well, that's an interesting interpretation. The central estimate might be a tiny cooling trend, but the error bars are huge. Furthermore, if you use UAH rather than RSS, you get substantially different estimates - given that, and the error bars, I'd be reluctant to make any statement based on those data.

JohnD - The science proving global warming is man-made, is skepticism at work. AGW (Global Warming as many call it), unlike the beliefs that Galileo also challenged, was not the accepted norm until very recently.

While the science of greenhouse gasses was settled science back in the 1800’s, when it came to the climate there were many competing scientific hypothesis as to what could/would and by how much affect something the size of the planet.

The threat of global warming, and the science to support AGW, only started to gain traction in the 70’s and it took until the 90’s before a consensus position was formed.

Even after overwhelming evidence with more and more discoveries being made, it is still an uphill battle against those wanting to cling to the old status quo.

Claiming that we should treat AGW with skepticism is like claiming that we should still treat the sun as the center of the solar system with skepticism.

Quick - Ask the denier why he is trying to pretend that the oceans below their surfaces do not exist?

Also ask him why anyone would go to wood for trees, or wherever, when they should only be going to the University of Alabama Huntsville for the University’s climate data to guarantee validity: http://nsstc.uah.edu/climate/

The fact that the oceans are storing the heat down to the 700 meter level is all the proof needed that global warming has not plateaued, but that it continues to trend upwards. Just because we now have to measure the oceans in 3D does not change the fact that the globe is warming. Added heat is added heat.

Claims/headlines that “NASA says heat not in deep ocean” are BS. No one has seriously claimed that from what I have read/heard/seen.

I am also certain that when enough energy is absorbed down to the 700 meter level that it starts to heat “the deep ocean” that the oceans will be literally boiling, or hot enough that we won’t care that it isn’t technically boiling, at the equator at the surface level.

Josh Willis clearly said that “The oceans are absorbing more than 80 percent of the heat from global warming. If you aren’t measuring heat content in the upper ocean, you aren’t measuring global warming.”

Obviously, this is the US only, but we also use more energy than anyone, esp 3rd world countries, so not sure the weight of this trend.

It seems we are doing the right things here according to this chart, and I dont suppose we'd want to encourage the 3rd world to give up their growing economies just because ours is mature and we are rich. Other modern countries are likely to have the same or better trends. So with warming ocurring, population growth slowing, not sure what valuable actions could be implemented (besides more people buying into the "be more responsible" lifestyle).

Response:

[PS] Fixed link, but this has nothing to do with the topic. Perhaps copy it to here because it will be deleted shortly.

I read the full von Storch interview from Der Spiegel in 2013 that Peter99 quotes above. The quote, though edited, is not taken out of context— Storch is merely demonstrating appropriate scientific restraint. He stated that if the observed "pause" continued for 5 years at most (i.e. by about 2018) then climate models will need significant revision. He said that models can barely account for the past 15 years' data (his term (translated) was "stagnation" which was shown in only 2% of his simulations). The revisions Storch suggested were not at the level of tweaks but were instead fundamental changes: either (a) our effect on the climate is less than we had thought; or (b) natural variation is much larger than we had thought. Does Storch's statement reflect the consensus view among climate scientists? Surely if Storch is an IPCC lead author then his view must be mainstream at least.

The interview responses from Storch should indicate to you that Storch is less inclined than most to see the dangers of AGW. Those who are less optimistic about the future that Storch would put it more strongly. Note Storch considers a conservative value for projected sea level rise is the way to handle uncertainty. Many would see that as a lack of caution, equivalent to playing Russian roulette.

When Storch is asked about the fix required if global surface temperature continues to lag model predictions, the specific area he describes (while starting by saying "Among other things,...") is an underestimation of ocean heat uptake. That doesn't really chime with your (a) weaker AGW than we thought or (b) more natural variation than we thought, although you do a fair job of reproducing Storch's specific comment.

Perhaps it is worth looking at what Storch et al (2013) - 'Can climate models explain the recent stagnation in global warming?' says on this same subject a few weeks after the interview. The paper's abstract concludes:-

"Of the possible causes of the inconsistency, the underestimation of internal natural climate variability on decadal time scales isa plausible candidate, but the influence of unaccounted external forcing factors or an overestimation of the model sensitivity to elevated greenhouse gas concentrations cannot be ruled out. The first cause would have little impact of the expectations of longer term anthropogenic climate change, but the second and particularly the third would."

The paper is very short and does not actually derive the conclusions quoted from the abstract here. However these conclusions are less ambiguous that the interview (perhaps it was meant as a direct clarification) and is a far stronger position from Storch (& his co-authors). I would suggest that to hear it from somebody so cautious about over-estimating AGW as Storch gives some cause for some concern, although note the prospect of a lower climate sensitivity (the one option that lessens AGW) is rewarded with the adjective "particularly".

MA Rodger@348Agree, Storch seems more conservative, arguably to the point of complacency, than many other experts in the field. (Evens so, in the interview he says his "instinct" is that we will have >= 2 deg C warming by 2100.)However, my question was about the state of the climate models. Storch, apparently a mainstream scientist in the field, says the climate models are nearly unable to reproduce current data, and if the trend continues, the models will require significant changes (the one specific change he mentions being better modeling of the role of the oceans.) Is this in fact consensus/ majority/ mainstream opinion among experts?

One correction to my comment @348. The Storch et al (2013) paper appears to predate the interview. This blog post seems to be saying Storch was trying to get it published in Nature but unsuccessfully. The blog post does provide Storch's position quite clearly. He in 2013 does not see the model mean as overstating the expected warming unless the period of lower rise in temperature continues. Since then 2014 was the warmest year on record & 2015 could well top that.

And the message in the blog post is to do with model data rather than the models themselves, "a wake-up call that scenarios have to be prepared better" rather than a problem with the models. I'd reckon, give the work addressing the discrepancy, that experts generally appear to see it the same way.